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Researchers at Swansea University, working with colleagues in Australia and the Seychelles, have announced the longest recorded migration for the green sea turtle, an endangered species. One of eight turtles which were tracked by satellite was found to have travelled 3979 km, from the Chagos Islands in the Indian Ocean, to the coast of Somalia in east Africa.
The research was reported in the latest issue of Conservation Biology. The team were investigating the effectiveness of marine protected areas, which have been set up by governments around the world over the last decade as part of efforts to reduce declines in ocean biodiversity.
Picture: a sea turtle about to enter the Indian Ocean on the island of Diego Garcia, with satellite aerial attached to its shell.
The green turtle breeds on the Chagos Islands, in the Chagos Archipelago protected area, which covers 640,000 km around the isolated islands, which lie in the middle of the Indian Ocean. When it was set-up in 2010 it was the world’s largest marine protected area and it supports some of the most pristine coral reefs.
The research team attached small tags to the shells of eight nesting turtles, allowing them to be followed by satellite for over a year. They found:
• 7 of the 8 tracked individuals migrated to distant foraging grounds which lay outside the protected area boundary.
• One turtle had travelled 3979 km to the coast of Somalia, the longest migration ever recorded and published.
• Only 1 of the 8 tracked turtles remained inside the protected area after the breeding season had finished.
Picture: : a sea turtle with seagrass, where it forages for food. Courtesy of BS and RD Kirkby
The research team are from Swansea University, Deakin University (Australia) and the Seychelles
Professor Graeme Hays, from the College of Science at Swansea University, said:
"The message from this research is that networks of small protected areas need to be developed alongside larger ones, so species which migrate over long distances can stay in safe zones for as much time as possible.
The Chagos Archipelago protected area certainly has huge conservation benefit. It protects coral reefs and other important habitats and species, and it will protect turtles during key periods of their lives: when they are nesting and when the eggs are incubating.
But international cooperation will be required to develop the network of small protected areas across the Indian Ocean which are needed to protect the turtles at other times in their lives."
Picture: Sea turtle and jellyfish - courtesy of BS and RD Kirkby
Nicole Esteban, a Swansea University researcher who has worked on the project, added:
“Green sea turtles are an iconic species, and their welfare tells us a lot about the health of our oceans.
They forage in seagrass meadows which are being depleted because of pollution and other man-made causes.
Our study helps determine the location of these important habitats, and also highlights the need to protect seagrass meadows, and make a network of small marine protected areas (MPAs).
The results of this research help us understand locations of foraging grounds of Green turtles in the wider Indian Ocean. We’re continuing to monitor turtles in Chagos, and results from our work will feed into the plans for conservation in the Chagos Marine Reserve.”
Facts about green sea turtles, from National Geographic:
• Green sea turtles (Chelonia Mydas) are reptiles whose ancestors evolved on land and took to the sea to live about 150 million years ago.
• Their average life span in the wild is over 80 years
• They grow up to 5ft (1.5 m) and weigh up to 700 lbs (317.5 kg)
• Like other sea turtles, the green turtle cannot pull its head into its shell.
• There are two types of green turtle: the Atlantic green turtle, normally found off the shores of Europe and North America, and the Eastern Pacific green turtle, which has been found in coastal waters from Alaska to Chile.
• Adult green turtles feed on sea grasses and algae. Juvenile green turtles, however, will also eat invertebrates like crabs, jellyfish, and sponges.
• Green turtles are an endangered species. Despite this, they are still killed for their meat and eggs. Their numbers are also reduced by boat propeller accidents and the destruction of nesting grounds by human encroachment.
- Monday 21 July 2014 14.22 BST
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